Flotation device

ABSTRACT

A flotation device is disclosed having first and second spaced-apart, elongated, substantially rigid structural members and a plurality of buoyancy tubes held in compression between the first and second structural members. The compression connection between the ends of the buoyancy tubes and the sides of the structural members in this configuration can improve the structural integrity of the flotation device. The structural members can be made of glue-laminated timber, which has high strength and stability. The buoyancy tubes can be made of high-density polyethylene. A deck structure can be supported on top of the first and second structural members. Thus, thermal welding of the deck structure to the buoyancy tubes typically can be avoided. A flotation assembly also is disclosed including two flotation devices connected by a flexible hinge assembly.

CROSS REFERENCE TO RELATED APPLICATION

This claims the benefit of the earlier filing date of prior U.S. Provisional Application No. 60/701,137, filed Jul. 20, 2005, which is incorporated herein by reference.

FIELD

This disclosure relates generally to flotation devices, such as flotation devices having multiple buoyancy tubes.

BACKGROUND

Floating docks with timber superstructures supported by hollow or foam-filled pipe displacement members have become commonplace due to their simplicity and ease of construction. Typically, these docks are constructed using rigid pipes, such as steel, corrugated aluminum or plastic pipes, arranged longitudinally along the dock axis in unit lengths of 20 to 60 feet. Since metal pipe materials are susceptible to the corrosive effects of salt water, the use of plastic pipe has become increasingly common. High-density polyethylene (HDPE), for example, is virtually unaffected by salt water or by solvents and chemicals often found in the marine environment. Also, HDPE pipe is readily available in a wide variety of diameters and wall thicknesses.

In the construction of floating docks, the formation of a flat deck over cylindrical pipes can be challenging. Some conventional floating docks include clamping devices affixed to the pipes to support the deck. Clamping devices, however, are prone to slip and can, in some cases, crush the pipes. Other conventional floating docks include saddle structures over the pipes. For example, certain floating docks manufactured by Ferguson Enterprises, Inc. (Washougal, Wash.) include thermally-welded saddles made from flat plates of the same basic material as the pipes (i.e., HDPE). The welds, however, may become fatigued and fail due to the repeated application of flexural forces. Moreover, unlike with steel and aluminum, there are few standards governing the welding of plastic materials. At a minimum, such welds must be carefully executed to minimize the risk of failure.

U.S. Pat. No. 6,796,262 (the '262 patent) discloses the arrangement of short sections of plastic pipe transversely across the width of a floating dock, rather than longitudinally. To join these short pipe sections, a longer, vertically disposed plate that is at least as wide as the pipe diameter is welded to both ends of the sections, joining them in ladder-rung fashion at both ends. These vertically oriented plastic plates, however, are susceptible to the above-mentioned bending stresses imposed by mooring forces and associated vertical and lateral loading cycles. For example, if a boat moored on one side of the dock is caused to move in the opposite direction of a boat (or pile anchorage) on the opposing side of the dock, it is possible, over time, to pull the vertically oriented plate away from the welded pipe ends, causing separation failure.

Due to production limitations in manufacturing HDPE plates, the assemblies disclosed in the '262 patent are typically limited to less than 20 feet in length. To form larger structures, the assemblies must be joined together, such as by butt-welding the plates of adjacent assemblies or by incorporating articulating connectors positioned at frequent intervals. Butt-welds can be weakened to the point of failure by repeated vertical or horizontal bending. The use of articulating connectors also can be disadvantageous. For example, the short (e.g., 10 to 20 foot) lengths of the assemblies often match ambient wave lengths. Thus, it is possible to cause a harmonic reaction, resulting in excessive pitching and rolling of the overall structure. This motion can be physically and mentally unsettling to boaters attempting to walk on the dock. In addition, typical articulating connectors require extensive anchorages and, therefore, contribute excessively to the cost of manufacturing the dock.

SUMMARY

Disclosed herein are embodiments of a flotation device and embodiments of a method for making the flotation device. The flotation device can include first and second spaced-apart, elongated, substantially rigid structural members and a plurality of buoyancy tubes positioned between the first and second structural members. Some embodiments also include a wale held in compression against an outer surface of the first or second structural member. The first and second structural members and or the wale can comprise GLULAM. In various embodiments, the first and second structural members are sized to either partially or completely cover the ends of the buoyancy tubes. The structural members also can be sized to extend substantially the entire length of the flotation device.

The buoyancy tubes can be oriented substantially perpendicular to and held in compression between the first and second structural members. In some embodiments, the buoyancy tubes comprise HDPE. The buoyancy tubes also can house foam cores to assist in flotation. To help resist shear forces, at least one of the buoyancy tubes can have a cross-sectional area from about 200 to about 100,000 square inches. Between the structural members, the buoyancy tubes can be arranged in parallel, transversely extending rows. In some embodiments, each row has at least first and second buoyancy tubes positioned end-to-end and separated by an intermediate structural member extending substantially perpendicular to the rows of buoyancy tubes. Some embodiments of the disclosed flotation device do not include any shear-resisting elements placed in compression between the first and second structural members that are not buoyancy tubes, tensioning members or intermediate structural members.

A deck structure can be supported on top of the first and second structural members. A utility tube can be positioned between at least a portion of the buoyancy tubes and the deck structure. In some embodiments, there are substantially no supports for the deck structure located between the first and second structural members that are not intermediate structural members.

The buoyancy tubes can be held in compression, for example, by a plurality of tensioning members secured to the first and second structural members. The tensioning members can comprise metal rods. In some embodiments, the tensioning members extend through the first and second structural members and are held in place against outer surfaces of the first and second structural members. For example, the tensioning members can have threaded end portions that are held in place against outer surfaces of the first and second structural members using nuts. Washers also can be included to distribute the force against a larger portion of the outer surfaces of the first and second structural members. In some embodiments, the tensioning members are positioned such that they would support the buoyancy tubes if the buoyancy tubes were not held in compression between the first and second structural members. For example, the tensioning members can be positioned around the circumference of each buoyancy tube.

The disclosed flotation devices can be made, for example, by positioning a plurality of buoyancy tubes between and substantially perpendicular to a pair of structural members and securing a plurality of tensioning members to the first and second structural members. The tensioning members then can be tightened to place the buoyancy tubes in compression between the structural members.

Also disclosed are embodiments of a flotation assembly. Some embodiments of the disclosed flotation assembly include first and second flotation devices each comprising a plurality of buoyancy tubes held in compression between structural members oriented substantially perpendicular to the buoyancy tubes. The first and second flotation devices can be connected by a flexible hinge assembly comprising an elastomeric material. In some embodiments, the flexible hinge assembly also includes plates secured to substantially vertically oriented major planar surfaces of the structural members of the first and second flotation devices. The flexible hinge assembly can include brackets secured to the plates. In these embodiments, the elastomeric material can be used to connect a bracket of the first flotation device to a bracket of the second flotation device. The elastomeric material can, for example, be a belting material having substantially horizontally oriented major planar surfaces. A gap-filling deck plank can be mounted above the belting material, such as using at least one bolt and a spacer disposed between the belting material and the gap-filling deck plank.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary side elevation view of an embodiment of the disclosed flotation device including rows of buoyancy tubes held under compression between structural members.

FIG. 2 is a transverse cross-sectional view of the flotation device of FIG. 1 taken along the line 2-2.

FIG. 3 is an enlargement of a portion of FIG. 2 where a lower tensioning rod is secured to a structural member.

FIG. 4 is an enlargement of a portion of FIG. 2 where an upper tensioning rod is secured to a wale.

FIG. 5 is a transverse cross-sectional view of an embodiment similar to the flotation device of FIGS. 1-4, but also including an intermediate structural member.

FIG. 6 is a transverse cross-sectional view of an embodiment similar to the flotation device of FIG. 5, but including two intermediate structural members.

FIG. 7 is a fragmentary side elevation view of another embodiment of the disclosed flotation device including rows of buoyancy tubes held under compression between wales.

FIG. 8 is a transverse cross-sectional view of the flotation device of FIG. 7 taken along the line 8-8.

FIG. 9 is an enlargement of a portion of FIG. 8 where two tensioning rods are secured to a wale.

FIG. 10 is a transverse cross-sectional view of an embodiment similar to the flotation device of FIG. 7-9, but also including an intermediate wale.

FIG. 11 is a top plan view of an embodiment of the disclosed flotation device shown without decking and having six rows of buoyancy tubes arranged as three pairs.

FIG. 12 is a fragmentary, longitudinal cross-sectional view of two flotation devices interconnected by a flexible hinge assembly, according to one embodiment.

FIG. 13 is an enlargement of the flexible hinge assembly shown in FIG. 12.

FIG. 14 is a fragmentary, longitudinal cross-sectional view of two flotation devices interconnected by a flexible hinge assembly, according to another embodiment.

FIG. 15 is a fragmentary, longitudinal cross-sectional view of an embodiment similar to the embodiment shown in FIG. 14, but having a different flexible hinge assembly.

DETAILED DESCRIPTION

Disclosed herein are embodiments of a flotation device, embodiments of a method for making the flotation device and embodiments of a flotation assembly. Some embodiments of the flotation device include structural members, which can, for example, be beams of glue-laminated (GLULAM) timber or concrete panels. GLULAM beams are available in a variety of lengths, such as 40 to 70 foot lengths. The disclosed embodiments also can include transversely-arranged buoyancy tube sections between the structural members. The buoyancy tube sections typically need not be bonded or secured to one another. Instead, the buoyancy tube sections, which may or may not have end caps welded to seal each end, can be captured by compression and bolt shear within the walls of opposing structural members. GLULAM beams, in particular, are of enormous structural value, and are capable of resisting cyclic loads, mooring loads and both vertical and horizontal bending forces common to marinas.

Certain conventional panelized wale floats that do not include buoyancy tubes use one or more tiers of flat-laid diaphragm plates placed in compression within a panel frame to maintain the strength and integrity of opposing wales under horizontal loading. However, under extreme conditions, vertical loading can cause racking in the vertical direction. In contrast to these conventional floats, some embodiments of the disclosed flotation device take advantage of the cross-sectional area of buoyancy tube sections to provide shear force resistance vertically as well as horizontally. Therefore, these embodiments better resist racking regardless of the direction of environmental forces, and can obviate the need for additional bulkheads or other shear-resistant elements to maintain the desired strength and integrity.

As used herein, the term “tube” refers to any elongated member with a hollow portion and is not limited to a cylindrical tube. Accordingly, the cross-sectional profile of the buoyancy tubes in disclosed embodiments can be any shape, such as a circle, square, rectangle, triangle, or various combinations thereof. In some embodiments, the cross-sectional area of the buoyancy tubes is from about 100 to about 100,000 square inches, such as from about 200 to about 100,000 square inches or from about 300 to about 100,000 square inches.

FIGS. 1 and 2 show a flotation device 100, according to one disclosed embodiment. The flotation device 100 can include an upper walking surface so as to form a floating dock or dock unit. The flotation device 100 includes a plurality of substantially parallel, transversely extending buoyancy tubes 102 equally spaced along its length. The buoyancy tubes 102 preferably are made of a strong, durable, and corrosion resistant polymeric material, such as HDPE, although other materials (e.g., metal) also could be used. In some embodiments, one or more of the buoyancy tubes 102 houses a structure that assists with flotation. For example, the buoyancy tubes 102 can be at least partially filled with an expanded polystyrene (EPS) foam core to increase the overall buoyancy of the flotation device 100.

First and second transversely spaced-apart structural members 104 and 106 extend the length of the flotation device 100 adjacent opposite ends of the buoyancy tubes 102. The structural members 104, 106 desirably are wooden or GLULAM timber beams, although other suitable materials also can be used. For example, the structural members 104, 106 can be vertically oriented concrete panels. In the embodiment shown in FIGS. 1 and 2, the structural members 104, 106 are sized to completely cover the ends of the buoyancy tubes 102. Thus, when secured, the structural members 104, 106 may serve to protect any structures within the buoyancy tubes 102, such as EPS foam cores. In some embodiments, the structural members 104, 106 form a substantially water-tight seal with open ends of the buoyancy tubes 102. For example, the structural members 104, 106, may secure an end cap against each open end of the buoyancy tubes 102.

At least one tensioning member, such as the illustrated tensioning rods 108, is used to place the buoyancy tubes 102 in compression between the structural members 104, 106. As shown, the tensioning rods 108 extend transversely across the flotation device 100 and through corresponding openings in the structural members 104, 106. The tensioning rods 108 can be made from any material with relatively high tensile strength, such as metal. In some embodiments, the tensioning rods 108 are made from a corrosion-resistant metal, such as stainless steel. The use of rigid tensioning rods 108 improves the strength of the overall flotation device 100. Flexible tensioning members, however, also can be used. For example, in some embodiments, the tensioning rods 108 are substituted with taut wires or cables.

FIG. 3 is an enlarged view of the point where one of the tensioning rods 108 extends through the first structural member 104. An end portion 110 of the tensioning rod 108 protrudes past the outer surface of the structural member 104. A nut 112 secured to the end portion 110 of the tensioning rod 108 can press a washer 114 against the outer surface of the structural member 104. This type of connection is included on each end of each tensioning rod 108. By tightening the nuts 112, the buoyancy tubes 102 can be compressed between the structural members 104, 106 to form a substantially rigid structure.

The structure created by compressively loading the structural members 104, 106 and the buoyancy tubes 102 is well suited to resist bending or racking of the flotation device 100 under vertical and horizontal loads. The cylindrical shape of the buoyancy tubes 102 in this embodiment makes them especially effective for resisting vertical and horizontal forces. Using the buoyancy tubes 102 as structural elements can obviate the need to provide bulkheads or other shear-resisting elements placed in compression inside the flotation device 100. Moreover, by using compression, the structural integrity of the flotation device 100 does not depend upon thermal welds between the buoyancy tubes 102 and other components. Thermal welds, such as thermal welds between HDPE shear panels and HDPE buoyancy tubes are particularly susceptible to failure.

As best shown in FIG. 1, the tensioning rods 108 desirably are circumferentially spaced around and in close proximity to the outer surface of the buoyancy tubes 102. The tensioning rods 108 can be positioned such that, if loss of compression should occur, they will retain the buoyancy tubes 102 in place between the structural members 104, 106. For example, in the illustrated embodiment, four tensioning rods 108 are evenly-spaced around the circumference of each buoyancy tube 102. Alternatively, the buoyancy tubes 102 can be held in place by three tensioning rods 108 or by more than four tensioning rods.

As shown in FIG. 2, the flotation device 100 can include a deck structure 116 supported on top of the structural members 104, 106. The deck structure 116 can be made from any suitable material, such as wood planks or plywood panels, and can have a non-skid top surface, such as a fiber cement surface. The deck structure 116 can be secured to the structural members 104, 106 using suitable techniques or mechanisms, such as by nailing or bolting the deck structure to the structural members. Because the deck structure 116 is supported by the structural members 104, 106, clamping devices or thermally welded saddles for mounting the deck structure to the buoyancy tubes 102 are not required. The flotation device 100 also can include first and second longitudinally-extending rubstrip wales 118, 120, which can be made, for example, of wood or GLULAM. In the embodiment shown in FIGS. 1 and 2, each of the wales 118, 120 is secured to the upper portion of the outer surface of one of the structural members 104, 106. The wales 118, 120 are held in place by additional tensioning rods 108. Bull rails 122 and cleats 124 can be secured to the wales 118, 120 with vertical bolts 126.

FIG. 4 is an enlarged view of the point where one of the tensioning rods 108 extends through the first wale 118. The end portion 110 of the tensioning rod 108 is recessed relative to the outside surface of the first wale 118 to prevent it from being sheared off by impact. As with the tensioning rods 108 around the buoyancy tubes 102, the tensioning rods securing the wales 118, 120 are held in place with nuts 112 and washers 114. The tensioning rods securing the wales 118, 120 are within a horizontal plane and positioned directly above the tensioning rods 108 around the buoyancy tubes 102.

FIG. 5 shows a flotation device 200, according to another embodiment. The flotation device 200 is similar to the flotation device 100 except that it includes a vertically disposed intermediate structural member 202. The intermediate structural member 202 extends along the length of the flotation device 200 between parallel buoyancy tubes 204 aligned end-to-end and spaced transversely of the length of the flotation device in rows. As in the flotation device 100 shown in FIGS. 1-4, first and second outer structural members 206, 208 are positioned along the ends of the buoyancy tubes 204. Tensioning rods 210 extend through holes in the intermediate structural member 202 and are secured on the outside surface of each outer structural member 206, 208. FIG. 5 also shows utility tubes 212 extending along the length of the flotation device 200 between the top of the buoyancy tubes 204 and the bottom of tensioning rods 210 securing first and second wales 214, 216. The utility tubes 212 can be used to safely isolate utility lines, such as electrical wires. The intermediate structural member 202 and first and second outer structural members 206, 208 desirably are wooden or GLULAM timber beams. Other suitable materials also can be used.

In the flotation device 200, each transverse row includes two buoyancy tubes 204. Other embodiments, however, can include more than two buoyancy tubes per row with transversely spaced-apart intermediate structural members extending between the adjacent ends of buoyancy tubes in each row. For example, FIG. 6 shows a flotation device 300 that is similar to the flotation device 200, except that it includes transverse rows of three buoyancy tubes 302 per row. Other embodiments can include four, five or an even greater number of buoyancy tubes per row.

FIGS. 7 and 8 show a flotation device 400, according to another embodiment. The embodiment shown in FIGS. 7 and 8 relies on first and second wales 402, 404 and buoyancy tubes 406 to create a structure capable of resisting racking from horizontal and vertical loads. In this embodiment, the first and second wales 402, 404 act as structural members. The flotation device 400 does not include full-size structural members, such as the structural members 104, 106 shown in FIGS. 1-4. Since the wales 402, 404 do not cover the entire open ends of the buoyancy tubes 406, end panels 408 can be secured to the ends of the buoyancy tubes by welding or by affixing suitable fasteners to seal the buoyancy tubes and thereby prevent the ingress of water. The end panels 408 can be made of the same material as the buoyancy tubes 406, such as HDPE. In the flotation device 400, the wales 402, 404, end panels 408 and buoyancy tubes 406 are held in compression by tensioning rods 410. Sets of two vertically aligned tensioning rods 410 are positioned between and on either side of the buoyancy tubes 406. Although the tensioning rods 410 do not cradle the buoyancy tubes 406, the buoyancy tubes can be retained in place in the event of a loss of compression by structurally connecting the buoyancy tubes to the end panels 408, such as by welding the buoyancy tubes to the end panels.

FIG. 9 is an enlarged view of the point where two of the tensioning rods 410 extend through the first wale 402. The end portions 412 of the tensioning rods 410 preferably are not recessed within the wales 402, 404, as this can affect the structural integrity of the wales. Instead, the end portions 412 of the tensioning rods 410 are surrounded by guards or rubstrips 414 to protect them from being sheared off by impact and to prevent damage to vessels docked alongside the flotation device. The guards or rubstrips 414 can be made of any suitable material, such as metal or rubber. In the illustrated embodiments, the guards or rubstrips 414 are narrow boards secured to the outer surfaces of the wales 402, 404, with holes to accommodate the end portions 412 of the tensioning rods 410. The end portions 412 of the tensioning rods 410 are secured by nuts 416 tightened against washers 418. The washers 418 are set into mortises or recesses cut into the wales 402, 404.

FIG. 10 shows a flotation device 500 that is similar to the flotation device 400, except that it includes a vertically disposed intermediate wale 502. As with the first and second outer wales 504, 506, the intermediate wale 502 desirably is wooden or a GLULAM timber beam. Other suitable materials also can be used. The intermediate wale 502 extends along the length of the flotation device 500 between buoyancy tubes 508 aligned end-to-end and spaced transversely of the length of the flotation device in rows. Tensioning rods 510 extend through holes in the intermediate wale 502 and are secured on the outside surface of each outer wale 504, 506. In the illustrated embodiment, each transverse row includes two buoyancy tubes 508. Other embodiments, however, can include more than two buoyancy tubes 508 per row with transversely spaced-apart intermediate wales 502 extending between the buoyancy tubes. For example, some embodiments may include four, five or an even greater number of buoyancy tubes 508 per row.

The disclosed flotation devices can include various arrangements of rows of buoyancy tubes. For example, some embodiments include evenly spaced rows of buoyancy tubes along their entire length. Other embodiments include grouped rows of buoyancy tubes with the spacing between the groups being greater than the spacing between individual tubes in each group. For example, FIG. 11 is a plan view of a flotation device 600 shown without the decking. The flotation device 600 includes six rows of buoyancy tubes 602 arranged as three groups. Each group includes two rows of buoyancy tubes 602. Each row includes four buoyancy tubes 602 in compression between first and second outer structural members 604, 606. Three intermediate structural members 608 extend along the length of the flotation device 600 between the buoyancy tubes 602 within each row. Tensioning rods 610 extend across the width of the flotation device 600 parallel to the rows of buoyancy tubes 602.

In the flotation device 600 shown in FIG. 11, the tensioning rods 610 hold all the elements together and provide structural support. The width of the buoyancy tubes 602 and the presence of multiple rows of buoyancy tubes 602 help to prevent racking. Additional structural support can be provided by decking extending between the structural members 604, 606, 608. The decking typically is oriented parallel to the rows of buoyancy tubes 602. For added protection against racking, cross braces can be included below the decking extending diagonally between the corners of the overall flotation device 600 or between each set of structural members 604, 606, 608.

The flotation device 600 shown in FIG. 11 includes tensioning rods 610 that extend across its entire width. Other embodiments may include tensioning members that extend across only a portion of the overall width of the flotation device. For example, some embodiments may include tensioning members that extend between an outer structural member and an intermediate structural member or between two intermediate structural members. In these embodiments, the combination of tensioning members may act to hold together the flotation device even though none or only a portion of the tensioning members extend across the entire width of the flotation device. Some embodiments include tensioning members that extend between two structural members without extending through any intervening structural members and other tensioning members that do extend through intervening structural members and are secured to the outermost structural members of the flotation device. Independently compressing the buoyancy tubes in this manner helps to prevent damage to one buoyancy tube from affecting other buoyancy tubes in the same row.

Multiple flotation devices can be interconnected to each other to form a dock assembly, preferably using flexible hinges. For example, FIG. 12 shows a dock assembly 700 including flotation devices 702 a, 702 b coupled at their adjacent ends by a flexible hinge assembly 704. The flotation devices 702 a, 702 b each are similar to the flotation device 100 shown in FIGS. 1-4. The flotation devices 702 a, 702 b, include, respectively, buoyancy tubes 706 a, 706 b, tensioning rods 708 a, 708 b, structural members 710 a, 710 b, and decking 712 a, 712 b. The buoyancy tubes 706 a, 706 b are shown with foam cores 714 a, 714 b, respectively.

The hinge assembly 704 interconnects the flotation devices 702 a, 702 b while allowing for relative listing and twisting of the flotation devices. An enlarged view of the hinge assembly 704 is shown in FIG. 13. The hinge assembly 704 includes a pair of outer, elongated T-shaped brackets 716 a, 716 b extending widthwise along the facing edges of the flotation devices 702 a, 702 b, respectively. The outer T-shaped brackets 716 a, 716 b are secured, respectively, to end plates 718 a, 718 b, which are secured, respectively, to the structural members 710 a, 710 b by end plate bolts 720 a, 720 b. The outer T-shaped brackets 716 a, 716 b can be secured to the end plates 718 a, 718 b, for example, by welding.

The outer T-shaped brackets 716 a, 716 b are secured to inner, elongated T-shaped brackets 722 a, 722 b, respectively, by inner bracket bolts 724 a, 724 b. The inner T-shaped brackets 722 a, 722 b are interconnected by one or more layers 726 (two layers shown in the illustrated embodiment) of flexible material extending along the length of the inner T-shaped brackets. The layers 726 overlap a horizontal flange portion of the inner T-shaped brackets 722 a, 722 b and are secured thereto by bolts 728 extending vertically through layers and the horizontal flange portion of the inner T-shaped brackets. The layers 726 can be made of any suitable natural or synthetic elastomeric material, such as rubber. In particular embodiments, the layers 726 are made of a strong, flexible belting material, such as PLYLON® fabric-carcassed, rubber belting material manufactured by the Goodyear Tire and Rubber Company of Akron, Ohio. As further shown in FIGS. 12 and 13, a center deck plank 730 can be mounted on a spacer 732 disposed above the hinge assembly 704 between adjacent ends of the flotation devices 702 a, 702 b so as to provide a walking surface over the gap between the flotation devices.

FIG. 14 shows another embodiment of a dock assembly. The illustrated dock assembly 800 includes two flotation devices 802 a, 802 b interconnected by a flexible hinge assembly 804. The flotation devices 802 a, 802 b each are similar to the flotation device 400 shown in FIGS. 7-9. The flotation devices 802 a, 802 b, include, respectively, wales 806 a, 806 b and decking 808 a, 808 b. The flotation device 802 a also is shown with a buoyancy tube 810 a, tensioning rods 812 a, and an end panel 814 a. The buoyancy tube 810 a is shown with a foam core 816 a. The hinge assembly 804 includes a pair of elongated U-shaped brackets 818 a, 818 b extending widthwise along the facing edges of the flotation devices 802 a, 802 b, respectively. The U-shaped brackets 818 a, 818 b are secured, respectively, to end plates 820 a, 820 b, which are secured, respectively, to the wales 806 a, 806 b by end plate bolts 822 a, 822 b. The U-shaped brackets 818 a, 818 b can be secured to the end plates 820 a, 820 b, for example, by welding.

The U-shaped brackets 818 a, 818 b also are secured to inner, elongated L-shaped brackets 824 a, 824 b, respectively, by inner bracket bolts 826 a, 826 b. The inner L-shaped brackets 824 a, 824 b are interconnected by one or more layers 828 (two layers shown in the illustrated embodiment) of flexible material extending along the length of the inner L-shaped brackets. The layers 828 overlap a horizontal flange portion of the inner L-shaped brackets 824 a, 824 b and are secured thereto by bolts 830 extending vertically through layers and the horizontal flange portion of the inner L-shaped brackets. The layers 828 can be made of any suitable natural or synthetic elastomeric material, such as rubber. In particular embodiments, the layers 828 are made of a strong, flexible belting material, such as PLYLON®. As further shown in FIG. 14, a center deck plank 832 can be mounted on a spacer 834 disposed above the hinge assembly 804 between adjacent ends of the flotation devices 802 a, 802 b so as to provide a walking surface over the gap between the flotation devices.

FIG. 15 shows another embodiment of a dock assembly. The illustrated dock assembly 900 includes two flotation devices 902 a, 902 b interconnected by a flexible hinge assembly 904. The flotation devices 902 a, 902 b each are similar to the flotation device 400 shown in FIGS. 7-9. The flotation devices 902 a, 902 b, include, respectively, wales 906 a, 906 b and decking 908 a, 908 b. The flotation device 902 a also is shown with a buoyancy tube 910 a, tensioning rods 912 a, and an end panel 914 a. The buoyancy tube 910 a is shown with a foam core 916 a. The hinge assembly 904 includes a pair of elongated U-shaped brackets 918 a, 918 b extending widthwise along the facing edges of the flotation devices 902 a, 902 b, respectively. The U-shaped brackets 918 a, 918 b are secured, respectively, to end plates 920 a, 920 b, which are secured, respectively, to the wales 906 a, 906 b by end plate bolts 922 a, 922 b. The U-shaped brackets 918 a, 918 b can be secured to the end plates 920 a, 920 b, for example, by welding. An elongated, elastomeric spacer element 924 is situated between and extends widthwise across the end faces of the flotation units 902 a, 902 b to prevent direct contact between the flotation devices 902 a, 902 b. The elastomeric spacer element 924 can be made of any suitable natural or synthetic elastomeric material, such as rubber. In particular embodiments, the elastomeric spacer element 924 is made of a strong, flexible belting material, such as PLYLON®. A plurality of bracket bolts 926 spaced along the lengths of the U-shaped brackets 918 a, 918 b and the elastomeric spacer element 924 extend through corresponding holes in the U-shaped brackets and the elastomeric spacer element and are tightened with nuts 928 to secure the flotation units 902 a, 902 b to each other.

EXAMPLES

The following examples are provided to illustrate certain particular embodiments of the disclosure. Additional embodiments not limited to the particular features described are consistent with the following examples.

Example 1

This example describes a specific embodiment of a flotation device similar to the flotation device 100 illustrated in FIGS. 1-4. The buoyancy tubes 102 are made of HDPE and each have a diameter of about 30 inches and a length of about 41 inches. The first and second structural members 104, 106 are made of GLULAM and each have a height of about 36 inches and a thickness of about five and one eighth inches. The tensioning rods 108 are galvanized metal rods with a thickness of about three quarters of an inch. The deck structure 116 is made up of 2×6 boards. The first and second wales 118, 120 are made of GLULAM and each have a height of about ten and one half inches and a thickness of about five and one eighth inches. The bull rails 122 are made of GLULAM and each have a height of about six and three quarter inches and a thickness of about six inches.

Example 2

This example describes a specific embodiment of a flotation device similar to the flotation device 400 illustrated in FIGS. 7-9. The first and second wales 402, 404 are made of GLULAM and each have a height of about 12 inches and a thickness of about five and one eighth inches. The buoyancy tubes 406 are made of HDPE and each have a diameter of about 24 inches and a length of about 38 inches. The tensioning rods 410 are galvanized metal rods with a thickness of three quarters of an inch.

In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. I therefore claim as my invention all that comes within the scope and spirit of these claims. 

1. A flotation device comprising: first and second spaced-apart, elongated, substantially rigid structural members; a plurality of buoyancy tubes positioned between the first and second structural members and oriented substantially perpendicular to the first and second structural members; and a plurality of tensioning members secured to the first and second structural members such that the buoyancy tubes are held in compression between the first and second structural members.
 2. The flotation device of claim 1, wherein the first and second structural members extend substantially the entire length of the flotation device.
 3. The flotation device of claim 1, wherein the first and second structural members are sized to completely cover the ends of the buoyancy tubes.
 4. The flotation device of claim 1, wherein the first and second structural members comprise glue-laminated timber.
 5. The flotation device of claim 1, wherein the buoyancy tubes comprise high-density polyethylene.
 6. The flotation device of claim 1, wherein the tensioning members comprise metal rods.
 7. The flotation device of claim 1, wherein the tensioning members are positioned such that they would support the buoyancy tubes if the buoyancy tubes were not held in compression between the first and second structural members.
 8. The flotation device of claim 1, wherein the buoyancy tubes house respective foam cores.
 9. The flotation device of claim 1, wherein the first and second structural members are sized to partially cover the ends of the buoyancy tubes.
 10. The flotation device of claim 1, wherein the buoyancy tubes are arranged in parallel, transversely extending rows, each row having at least first and second buoyancy tubes positioned end-to-end and separated by an intermediate structural member extending substantially perpendicular to the rows of buoyancy tubes.
 11. The flotation device of claim 1, wherein the flotation device does not include any shear-resisting elements placed in compression between the first and second structural members that are not buoyancy tubes, tensioning members or intermediate structural members.
 12. The flotation device of claim 1, wherein the tensioning members extend through the first and second structural members and have nuts tightened on their outer end portions to place the buoyancy tubes in compression between the first and second structural members.
 13. The flotation device of claim 1, further comprising a wale held in compression against an outer surface of the first or second structural member.
 14. The flotation device of claim 1, wherein the cross-sectional area of at least one of the buoyancy tubes is from about 200 to about 100,000 square inches.
 15. The flotation device of claim 1, further comprising a deck structure supported above the first and second structural members.
 16. The flotation device of claim 15, having substantially no supports for the deck structure located between the first and second structural members that are not intermediate structural members.
 17. The flotation device of claim 15, further comprising a utility tube positioned between at least a portion of the buoyancy tubes and the deck structure.
 18. A flotation device comprising: first and second spaced apart, elongated, substantially rigid structural members comprising glue-laminated timber; and a plurality of buoyancy tubes positioned between the first and second structural members and extending in a direction that intersects the first and second structural members.
 19. The flotation device of claim 18, wherein the buoyancy tubes comprise high-density polyethylene.
 20. The flotation device of claim 18, wherein the buoyancy tubes are arranged in parallel, transversely extending rows, each row having at least first and second buoyancy tubes positioned end-to-end and separated by an intermediate structural member extending substantially perpendicular to the rows of buoyancy tubes.
 21. The flotation device of claim 18, wherein the cross-sectional area of at least one of the buoyancy tubes is from about 200 to about 100,000 square inches.
 22. The flotation device of claim 18, further comprising a deck structure supported above the first and second structural members.
 23. The flotation device of claim 22, having substantially no supports for the deck structure located between the first and second structural members that are not intermediate structural members.
 24. The flotation device of claim 18 in combination with another flotation device, the flotation devices interconnected by a flexible hinge assembly.
 25. The combination of claim 24, wherein the flexible hinge assembly comprises at least a piece of a flexible belting material connected to each flotation device.
 26. A flotation device comprising: a plurality of buoyancy tubes; and means for holding the buoyancy tubes in compression.
 27. A flotation assembly comprising: a first flotation device comprising a plurality of buoyancy tubes held in compression between structural members oriented substantially perpendicular to the buoyancy tubes; a second flotation device comprising a plurality of buoyancy tubes held in compression between structural members oriented substantially perpendicular to the buoyancy tubes; and a flexible hinge assembly attaching the first flotation device to the second flotation device, wherein the flexible hinge assembly comprises an elastomeric material.
 28. The flotation assembly of claim 27, wherein the flexible hinge assembly further comprises plates secured to substantially vertically oriented major planar surfaces of the structural members of the first and second flotation devices.
 29. The flotation assembly of claim 28, wherein the flexible hinge assembly further comprises brackets secured to the plates, and the elastomeric material connects a bracket of the first flotation device to a bracket of the second flotation device.
 30. The flotation assembly of claim 27, wherein the flexible hinge assembly comprises a belting material having substantially horizontally oriented major planar surfaces and a gap-filling deck plank mounted above the belting material.
 31. The flotation assembly of claim 30, wherein the gap-filling deck plank is secured to the belting material with at least one bolt and the flexible hinge assembly further comprises a spacer positioned between the gap-filling deck plank and the belting material.
 32. A method for making a flotation device comprising, positioning a plurality of buoyancy tubes between and substantially perpendicular to a pair of structural members; securing a plurality of tensioning members to the first and second structural members; and tightening the tensioning members to place the buoyancy tubes in compression between the structural members. 